Thursday, July 16, 2009

QOS - MQC shape average vs shape peak

The operation of shape peak is exactly the same as shape average:it calculates the default bc in the same manner, except, that each interval it gets to fill up the Be bucket as well. With the shape average command the excess burst is only sent if the bc bucket is full i.e. after periods of inactivity.

If a network has additional bandwidth available (over the provisioned CIR) and the application can tolerate occasional packet loss, the extra bandwidth can be exploited through the use of peak rate shaping. There may be occasional packet drops when network congestion occurs.

If the traffic being sent to the network must strictly conform to the configured network provisioned CIR, then use average traffic shaping.

If you had: shape peak 8000

We get a default tc of 1/8th of a second which gives us a bc of 1000 and a be of the same value. So the sending rate equals bc + be per tc or 16000. The rate equation is as follows